evilcry2012的專欄
Java IO開銷測試比較
2015年02月08日 19:43:27 飛火流雲 閱讀數：444更多
修改了下程式碼:-
<pre name="code" class="java">package ringBuffer; -
import java.io.BufferedWriter; -
import java.io.FileNotFoundException; -
import java.io.FileOutputStream; -
import java.io.FileWriter; -
import java.io.IOException; -
import java.io.OutputStreamWriter; -
import java.io.RandomAccessFile; -
import java.nio.MappedByteBuffer; -
import java.nio.channels.FileChannel; -
import java.nio.channels.FileChannel.MapMode; -
public class PerformanceWriteTest { -
/** -
* @param args -
*/ -
public static void main(String[] args) { -
String outputFile = "F:\\test\\ioTest.txt"; -
Long length = 0L ; -
Long totalTime = 0L; -
try { -
raf = new RandomAccessFile("F:\\test\\ioTest.txt", "rw"); -
FileChannel fc = raf.getChannel(); -
mbb = fc.map(MapMode.READ_WRITE, 0, 85*1024*1024); -
} catch (FileNotFoundException e) { -
e.printStackTrace(); -
} catch (IOException e) { -
e.printStackTrace(); -
} -
for (int j = 0; j < 5; j++) { -
// for (int j = 0; j < 5; j++) { -
StringBuffer sb = new StringBuffer(); -
for (Integer i = 0; i < 1000000; i++) { -
// for (Integer i = 0; i < 100000; i++) { -
sb.append(j+i.toString() + "V"); -
} -
sb.append("S"); -
// byte[] msgs = sb.toString().getBytes(); -
length = (long) sb.toString().length() ; -
long start = System.currentTimeMillis() ; -
appendFileTest(outputFile,sb.toString()); -
totalTime = totalTime + (System.currentTimeMillis() - start) ; -
} -
System.out.println(" Total Data is : " + length*5/1000 + " Kbytes! ") ; -
System.out.println(" Total Time is : " + totalTime) ; -
System.out.println(" Averge Speed is :" + length*5/(totalTime*1000) + " Kbytes"); -
} -
private static void appendFileTest(String outputFile, String msgs) { -
// append1(outputFile, msgs) ; //FileOutputStream -
// append2(outputFile, msgs) ; //FileWriter -
// append3(outputFile, msgs) ; //RandomAccessFile -
append4(outputFile, msgs) ; //RandomAccessFile -
} -
private static void append1(String outputFile, String msgs) { -
BufferedWriter out = null; -
try { -
out = new BufferedWriter(new OutputStreamWriter( -
new FileOutputStream(outputFile, true))); -
out.append(msgs) ; -
} catch (Exception e) { -
e.printStackTrace(); -
} finally { -
try { -
out.close(); -
} catch (IOException e) { -
e.printStackTrace(); -
} -
} -
} -
private static void append2(String outputFile, String msgs) { -
try { -
FileWriter writer = new FileWriter(outputFile, true); // 開啟一個寫檔案器，建構函式中的第二個引數true表示以追加形式寫檔案 -
writer.write(msgs); -
writer.close(); -
} catch (IOException e) { -
e.printStackTrace(); -
} -
} -
private static void append3(String outputFile, String msgs) { -
try { -
RandomAccessFile randomFile = new RandomAccessFile(outputFile, "rw"); // 開啟一個隨機訪問檔案流，按讀寫方式 -
long fileLength = randomFile.length(); // 檔案長度，位元組數 -
randomFile.seek(fileLength); // 將寫檔案指標移到檔案尾 -
randomFile.writeBytes(msgs); -
randomFile.close(); -
} catch (IOException e) { -
e.printStackTrace(); -
} -
} -
private static void append4(String outputFile, String msgs) { -
try { -
mbb.position(pos) ; -
mbb.put(msgs.getBytes()); -
pos = pos + msgs.getBytes().length ; -
raf.close(); -
} catch (IOException e) { -
e.printStackTrace(); -
} -
} -
static RandomAccessFile raf ; -
static MappedByteBuffer mbb ; -
static Integer pos = 0 ; -
}
測試時為了增加記憶體開銷，增加了 -XX:+PrintGC 選項，如果大家知道更好的測試記憶體消耗的方法，請告訴我哈。-
</pre><pre code_snippet_id="600488" snippet_file_name="blog_20150208_4_5933734" name="code" class="java">[GC 32704K->2872K(124992 K), 0.0015308 secs] -
[GC 35576K->5152K(157696K), 0.0018430 secs] -
[GC 70560K->9768K(157696K), 0.0032342 secs] -
[GC 75176K->28240K(223104K), 0.0056030 secs] -
[GC 159056K->28888K(223104K), 0.0009104 secs] -
[GC 159704K->37464K(353856K), 0.0033345 secs] -
[GC 299096K->42152K(354048K), 0.0022436 secs] -
[GC 303784K->39848K(615 744K), 0.0009303 secs] -
[GC 563112K->55968K(616 192K), 0.0087540 secs] -
Total Data is : 39444 Kbytes! -
Total Time is : 159 -
Averge Speed is :248 Kbytes -
2.826G -
[GC 32704K->2872K(124992K), 0.0136790 secs] -
[GC 35576K->5184K(157696K), 0.0019457 secs] -
[GC 70592K->9792K(157696K), 0.0031822 secs] -
[GC 75200K->28240K(223104K), 0.0056500 secs] -
[GC 152655K->43624K(223104K), 0.0051765 secs] -
[GC 174440K->52848K(353856K), 0.0034980 secs] -
[GC 314480K->55276K(354176K), 0.0013858 secs] -
[GC 314139K->71372K(615488K), 0.0058115 secs] -
[Full GC 71372K->18926K(610816K), 0.0094205 secs] -
[GC 542190K->43678K(610880K), 0.0038294 secs] -
Total Data is : 39444 Kbytes! -
Total Time is : 153 -
Averge Speed is :257 Kbytesa -
3.43G -
[GC 32704K->2872K(124992K), 0.0012018 secs] -
[GC 35576K->5184K(124992K), 0.0021390 secs] -
[GC 37888K->9800K(124992K), 0.0031359 secs] -
[GC 42504K->9824K(157696K), 0.0005724 secs] -
[GC 75232K->28208K(157696K), 0.0059463 secs] -
[GC 93616K->28224K(223040K), 0.0007707 secs] -
[GC 159040K->32852K(223360K), 0.0095536 secs] -
[GC 163668K->46740K(354880K), 0.0055367 secs] -
[GC 308372K->55892K(355008K), 0.0032216 secs] -
[GC 317524K->60484K(511168K), 0.0017500 secs] -
[GC 478468K->65092K(511808K), 0.0033206 secs] -
Total Data is : 39444 Kbytes! -
Total Time is : 68 -
Averge Speed is :580 Kbytes -
2.87G
-
[GC 32704K->2880K(124992K), 0.0132009 secs] -
[GC 35584K->5192K(157696K), 0.0017013 secs] -
[GC 70600K->9800K(157696K), 0.0035649 secs] -
[GC 75208K->28232K(223104K), 0.0057867 secs] -
[GC 151138K->43680K(223104K), 0.0055066 secs] -
[GC 174496K->48256K(353344K), 0.0020662 secs] -
[GC 298339K->59048K(354496K), 0.0054248 secs] -
[GC 319528K->77512K(614592K), 0.0058665 secs] -
[Full GC 77512K->18933K(612224K), 0.0097774 secs] -
[GC 521588K->34405K(612352K), 0.0027320 secs] -
Total Data is : 39444 Kbytes! -
Total Time is : 137 -
Averge Speed is :287 Kbytes -
3.4G
這裡很奇怪，理論上Mbb的效能應該遠大於這個，可能是我的測試資料量太小的緣故.綜上可見，RandomAccessFile 價效比最高。